JP7315329B2 - Electronic equipment with liquid crystal display and imaging function - Google Patents

Description

An embodiment of the present invention relates to the arrangement of image sensors provided in an electronic device. Further, one embodiment of the present invention relates to a configuration of a liquid crystal display panel and a lighting unit in a liquid crystal display device.

As electronic devices that digitally process information and electrically analogize video and/or audio, multifunctional mobile phones called smartphones and keyboardless portable terminals called tablet terminals are widely used in social life. In such an electronic device, cameras are mounted on both the front side and the back side when the side on which the display screen is provided is the front side. A camera arranged on the front side of the electronic device is arranged in the frame portion of the housing surrounding the display screen. In an electronic device, the frame portion (also called picture frame) surrounding the display screen needs to secure a certain area for arranging the camera. Therefore, there is a limit to narrowing the frame portion of the housing of the electronic device, and mounting a camera that captures an image of the front hinders the narrowing of the frame.

By the way, Japanese Patent Laid-Open No. 2003-100000 discloses an image capturing and displaying system in which a video camera is arranged on the back of a liquid crystal display panel and configured to capture an image of an object through a display screen. However, the image capturing and displaying system disclosed in Patent Document 1 needs to alternately switch between the image display mode of the liquid crystal panel and the image capturing mode of the video camera, which poses a problem that image display and image capturing cannot be performed at the same time.

JP-A-7-131766

An object of one embodiment of the present invention is to achieve a narrow frame in an electronic device in which a camera is arranged on the side where a display screen is provided. Another object of one embodiment of the present invention is to provide an electronic device and a display device capable of displaying an image and capturing an image at the same time.

An electronic device according to an embodiment of the present invention includes a liquid crystal display panel having a display area in which a plurality of pixels are arranged, an imaging device arranged on the back side of the liquid crystal display panel and capturing an image of the front through the display panel, and an illumination unit arranged between the liquid crystal display panel and the imaging device.
The imaging element is arranged in an area overlapping the display area, and the illumination unit includes an optical modulation element arranged so as to overlap the display area, and a light source for illuminating the optical modulation element.

A liquid crystal display device according to an embodiment of the present invention includes a liquid crystal display panel having a display area in which a plurality of pixels are arranged, and an illumination unit arranged to overlap the liquid crystal display panel. The illumination unit includes a light modulation element arranged to overlap the display area and a light source for illuminating the light modulation element, and the light modulation element can be partially controlled between a scattering state and a transmission state in the area overlapping the display area.

1 is a perspective view showing main components of an electronic device according to an embodiment of the invention; FIG. 1 shows the configuration of an electronic device according to an embodiment of the present invention, where (A) is a front view, and (B) is a schematic cross-sectional view showing the arrangement of a cover panel, a liquid crystal display device, and an imaging element; 1 is a schematic cross-sectional view showing the configuration of an electronic device according to an embodiment of the present invention, showing the arrangement of a liquid crystal display device and an imaging device, and the state when the imaging device captures an image; FIG. 4A and 4B are cross-sectional views illustrating the operation of the lighting unit provided in the electronic device according to the embodiment of the present invention, where (A) shows the state in the non-imaging mode, and (B) shows the state in the imaging mode; It is a figure explaining operation|movement of the electronic device which concerns on one Embodiment of this invention. FIG. 4 is a diagram showing an example of an image displayed in the display area when the electronic device according to one embodiment of the present invention is in imaging mode; It is a figure explaining operation|movement of the electronic device which concerns on one Embodiment of this invention. It is a figure explaining operation|movement of the electronic device which concerns on one Embodiment of this invention. It is a figure explaining operation|movement of the electronic device which concerns on one Embodiment of this invention. It is a figure explaining operation|movement of the electronic device which concerns on one Embodiment of this invention. 1 is a block diagram showing the configuration of an electronic device according to an embodiment of the invention; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different aspects and should not be construed as being limited to the description of the embodiments exemplified below. In order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, the same reference numerals (or numerals followed by a, b, etc.) are attached to the same elements as those described above with respect to the previous figures, and detailed description may be omitted as appropriate. In addition, the letters "first" and "second" for each element are convenient labels used to distinguish each element and have no further meaning unless otherwise specified.

In this specification, when a member or region is “above (or below)” another member or region, unless otherwise specified, this includes not only the case of being directly above (or directly below) the other member or region, but also the case of being above (or below) the other member or region, that is, above (or below) the other member or region. In the following description, unless otherwise specified, the side on which the touch sensor is provided with respect to the base member in a cross-sectional view is referred to as "upper" or "upper", the surface viewed from "upper" or "above" is referred to as "upper" or "upper surface side", and the reverse is referred to as "lower", "lower", "lower surface" or "lower surface side".

FIG. 1 is a perspective view showing main components of an electronic device 100 according to one embodiment of the invention. The electronic device 100 includes a liquid crystal display device 102 and imaging elements 104 and 105 . The liquid crystal display device 102 includes a liquid crystal display panel 110 and an illumination unit 112 . The liquid crystal display panel 110 is arranged on the front side of the lighting unit 112, and the lighting unit 112 illuminates the liquid crystal display panel 110 from the rear side.

The liquid crystal display panel 110 has a display area 114 in which a plurality of pixels are arranged. The lighting unit 112 includes a light source 118 and a light modulation element 120 . The light modulation element 120 has a planar region from which illumination light is emitted, and is arranged so that the light emission surface overlaps with the liquid crystal display panel 110 . The illumination unit 112 illuminates the display area 114 of the liquid crystal display panel 110 from behind.

In one embodiment of the present invention, the light modulation element refers to an element that can be controlled between a state of scattering light and a transparent state without scattering light. For example, the light modulating element is implemented by an element containing an electro-optic material whose optical properties are changed by electrical energy. The light modulation element has the function of controlling the light intensity distribution in the light emitting plane by such an electro-optical action.

A cover panel 106 is provided as an arbitrary member on the front surface of the liquid crystal display device 102 . The cover panel 106 is formed of a transparent member made of glass, plastic, or the like. Electronic device 100 has a display screen formed by liquid crystal display device 102 , and a user views an image displayed on the display screen through cover panel 106 .

The imaging element 104 is arranged on the back side of the liquid crystal display device 102 . The imaging element 104 is arranged at a position overlapping the display area 114 . The light-receiving surface of the imaging element 104 is directed so as to image the front of the liquid crystal display device 102 (the side on which the cover panel 106 is provided). The light-receiving surface of the imaging device 105 is directed so as to pick up an image in the rear direction opposite to the imaging device 104 . The liquid crystal display device 102 and imaging elements 104 and 105 are housed in a housing 108 . The imaging element 104 is arranged so as not to be seen from the outside when housed inside the housing 108 .

In the lighting unit 112 , the light source 118 is arranged on the lateral side of the light modulation element 120 . A light emitting diode (LED) or a cold cathode tube is used for the light source 118 . The light source 118 includes, for example, a plurality of light emitting diodes arranged along one side of a rectangular light modulation element 120 . The light from the light source 118 is incident on the light modulation element 120 from the side. The light incident on the light modulation element 120 is internally diffused and scattered, and emitted to the side where the liquid crystal display panel 110 is arranged.

The imaging element 104 is arranged in a region overlapping the display region 114 of the liquid crystal display panel 110 . The imaging device 104 receives external light that has passed through the liquid crystal display panel 110 and the light modulation device 120 and takes an image. The imaging element 104 is formed of, for example, a CCD (Charged Coupled Devices) type or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor.

In this way, the electronic device 100 according to one embodiment of the present invention is arranged at a position where the imaging element 104 is housed in the housing 108, the front surface is covered with the liquid crystal display panel 110, the lighting unit 112, and the cover panel 106, so that the electronic device 100 is not exposed to the outside and is not directly viewed by the user. Since the imaging element 104 is not arranged in the frame portion of the housing 108 surrounding the display area 114, the electronic device 100 according to the embodiment of the present invention can achieve a narrow frame.

FIG. 2A shows the electronic device 100 viewed from the front. In the electronic device 100, the liquid crystal display device 102 and the imaging element 104 are arranged on the back side of the cover panel 106 so as to overlap each other. A display area 114 is formed by the liquid crystal display device 102 in the plane of the cover panel 106 . An area surrounding the display area 114 is a non-display area 116 that does not directly contribute to display. The non-display area 116 surrounds the image displayed in the display area 114 and is sometimes referred to as a picture frame or picture frame area. Note that FIG. 2A shows a mode in which a non-display area 116 is provided so as to surround the entire periphery of the display area 114 . However, this aspect is an example, and one embodiment of the present invention is not limited to this aspect. For example, the electronic device 100 may have a configuration in which substantially the entire surface is the display area 114 when viewed from the front, and the non-display area 116 is not visible.

The imaging element 104 is not arranged in the non-display area 116 but is arranged in an area overlapping the display area 114 . The imaging device 104 is arranged on the back side of the liquid crystal display panel 110 so as not to affect visual recognition of the image. Therefore, when an image is displayed on the display area 114 , the user of the electronic device 100 does not visually recognize the position of the imaging element 104 through the display area 114 . The imaging device 104 is arranged at an arbitrary position in the region overlapping the display region 114 . For example, the imaging element 104 may be arranged in the center of the display area 114 or may be arranged near the periphery of the display area 114 . Also, a plurality of imaging elements 104 may be arranged within the plane of the display area 114 .

FIG. 2B shows a schematic cross-sectional view showing the main configuration of the electronic device 100. As shown in FIG. FIG. 2B shows the arrangement of the cover panel 106, the liquid crystal display device 102, and the imaging element 104. FIG. The liquid crystal display device 102 includes a liquid crystal display panel 110 and an illumination unit 112 . In the electronic device 100, the cover panel 106, the liquid crystal display device 102, and the imaging device 104 are stacked in this order from the viewing side. When viewed from the viewing side, the illumination unit 112 illuminates the liquid crystal display panel 110 from the rear side (the side opposite to the side on which the cover panel 106 is arranged). The liquid crystal display panel 110 modulates transmitted light using the electro-optical effect of liquid crystal and displays an image on the display area 114 .

The liquid crystal display panel 110 has a structure in which a first substrate 122 and a second substrate 124 are provided, and a liquid crystal layer 128 is provided between the first substrate 122 and the second substrate 124 . In the liquid crystal layer 128 , the alignment state of liquid crystal molecules is controlled by the pixel electrodes 126 . A pixel electrode 126 is provided corresponding to each of the plurality of pixels forming the display region 114 . Although not shown in detail in FIG. 2B, the pixel electrode 126 has a structure corresponding to various liquid crystal modes. For example, the pixel electrode 126 has a configuration compatible with various systems such as an IPS (In Plane Switching) system, a VA (Vertical Alignment) system, an MVA (Multi-domain Vertical Alignment) system, and a TN (Twisted Nematic) system.

In the illumination unit 112, the illumination light incident on the light modulation element 120 from the light source 118 is diffused and scattered in the plane, and is emitted to the liquid crystal display panel 110 side. The light modulation element 120 has a function of electrically controlling a part or the entire surface between a scattering state for scattering light and a transmission state for transmitting light.

The imaging element 104 is arranged on the back side of the liquid crystal display device 102 (the side opposite to the side on which the cover panel 106 is arranged). Since the imaging element 104 is arranged in an area overlapping with the display area 114 , at least the liquid crystal display panel 110 and the light modulation element 120 are arranged in front of the imaging element 104 (on the imaging side). When the light modulation element 120 is in the scattering state, external light (light incident from the outside of the cover panel 106 ) is scattered by the light modulation element 120 , and at least direct light does not enter the imaging element 104 . Therefore, when the light modulation element 120 is controlled to the scattering state, the imaging element 104 cannot image the front of the liquid crystal display panel 110 . On the other hand, when the light modulation element 120 is controlled to be in a transmission state, it is possible to allow external light to enter the imaging element 104 . Therefore, by controlling the optical state of the light modulation element 120, the electronic device 100 can appropriately display and capture an image.

Next, a basic operation of electronic device 100 will be described. FIG. 2B shows a state in which an image is displayed on the entire display area 114 . In this state, the light modulating element 120 illuminates the entire display area 114 of the liquid crystal display panel 110 . In this state, the imaging element 104 cannot image the front of the liquid crystal display panel 110 because the light modulation element 120 on the front side is controlled to be in a scattering state. Therefore, such a state in electronic device 100 can be called a non-imaging mode.

FIG. 3 shows a state in which the optical state of the light modulation element 120 is controlled from the scatterers to the transmission state in the area overlapping the imaging element 104 (the front area of the imaging element 104). As shown in FIG. 3, the light modulation element 120 is not entirely in a transparent state, but is controlled so as to form a partially transparent state so that external light can enter the imaging surface of the imaging element 104. Therefore, this state in light modulating element 120 can also be referred to as a partially transmissive state. Also, FIG. 3 shows a state in which the orientation of the liquid crystal is controlled so that the pixels in the area of the liquid crystal display panel 110 overlapping the imaging element 104 display white (transmissive state). By such control, the imaging element 104 enters a state in which external light is incident from the viewing side through the liquid crystal display panel 110 and the light modulation element 120 . In this mode, the imaging element 104 is in a state capable of imaging the area in front of the liquid crystal display panel 110 . Therefore, such a state in electronic device 100 can be called an imaging mode.

Note that even in the imaging mode, the light modulation element 120 can maintain the scatter in the area not overlapping the imaging element 104, and the liquid crystal display panel 110 can display the image of the display area 114. Therefore, in the imaging mode, it is possible to perform not only imaging but also display of images at the same time.

4A and 4B are cross-sectional views illustrating the operation of the lighting unit 112. FIG. FIG. 4A shows the state in the non-imaging mode, and FIG. 4B shows the state in the imaging mode. The light modulation element 120 has a configuration in which a light modulating layer 134 is provided between a third substrate 130 and a fourth substrate 132 arranged to face the third substrate 130 . A first electrode 138 is provided on the third substrate 130 and a second electrode 140 is provided on the fourth substrate 132 . Both the first electrode 138 and the second electrode 140 are formed of a transparent conductive film. The first electrode 138 is provided as a common electrode extending over substantially the entire surface of the third substrate 130, and the second electrode 140 is provided corresponding to the position where the imaging device 104 is arranged and is electrically isolated from other regions. Here, in the following description, in the light modulation element 120, the region where the first electrode 138 and the second electrode 140 overlap is called a first region 201, and the other region is called a second region 202.

The light control layer 134 has the property of forming at least two states, a scattering state that scatters light and a transparent state that transmits light. Such a light control layer 134 is formed using, for example, polymer dispersed liquid crystal. A polymer-dispersed liquid crystal is a liquid crystal in which a polymer network structure is formed. The polymer-dispersed liquid crystal has the effect of inducing an irregular arrangement of the liquid crystal molecules 136 by the action of the polymer network to scatter light. On the other hand, the polymer-dispersed liquid crystal exhibits the effect of transmitting the light without scattering it when the liquid crystal molecules 136 are oriented in one direction by applying a voltage. Polymer-dispersed liquid crystals are classified into those called normally white types that change from a scattering state to a transparent state by applying a voltage, and normally black types that change from a transparent state to a scattering state by applying a voltage (also called reverse mode). In one embodiment of the present invention, the light control layer 134 can use both normally white type and normally black type polymer dispersed liquid crystals.

FIG. 4A shows the case where the light control layer 134 is provided with a normally white polymer-dispersed liquid crystal. FIG. 4A also shows a non-imaging mode, in which no voltage is applied between the first electrode 138 and the second electrode 140. FIG. In this state, the light modulating layer 134 is in a scattering state both in the first region 201 and the second region 202 . That is, the polymer-dispersed liquid crystal is in a state in which the liquid crystal molecules 136 are oriented in random directions to scatter light. Therefore, the light incident on the light modulation element 120 from the light source 118 is diffused and scattered in the light modulating layer 134 and irradiated in the direction of the liquid crystal display panel 110 .

FIG. 4B shows an imaging mode in which a voltage is applied between the first electrode 138 and the second electrode 140 in the first region 201 and still no voltage is applied in the second region 202 . In the dimming layer 134, the first region 201 changes to a transparent state, and the second region 202 maintains a scattering state. That is, in the polymer-dispersed liquid crystal, the liquid crystal molecules 136 are oriented in one direction under the action of an electric field in the region sandwiched between the first electrode 138 and the second electrode 140 . Since the alignment of the liquid crystal molecules 136 is aligned in the first region 201, the effect of scattering light is reduced and the first region 201 becomes transparent.

As a result, the light modulation element 120 becomes transparent in the first region 201 located in front of the image pickup element 104, and enters a state in which external light can enter. On the other hand, the second region 202 remains in a scattering state because the liquid crystal molecules 136 are still randomly oriented. Thereby, the second area 202 can illuminate the liquid crystal display panel 110 , and the liquid crystal display panel 110 can display an image in an area corresponding to the second area 202 .

In this way, the lighting unit 112 can switch between the non-imaging mode and the imaging mode by partially controlling the scattering state and the transparent state using the light modulation element 120 . In the imaging mode, it is possible to perform imaging using the imaging device 104 while displaying an image in the display area 114 by the liquid crystal display panel 110 .

The second electrode 140 may be formed on substantially the entire surface of the fourth substrate 132 instead of being provided as an individual electrode that is distinguished from other regions. According to such a configuration, the entire light modulation element 120 is simultaneously controlled between the scattering state and the transparent state. In this case, the image display by the liquid crystal display panel 110 and the imaging by the imaging device 104 can be alternately performed. Further, the light modulation element 120 may have a passive matrix electrode structure. The light modulation element 120 can control the scattering state and the transmission state in the region corresponding to the first region 201 by including passive matrix electrodes.

FIG. 5 is a diagram explaining the operation of the electronic device according to one embodiment of the present invention. FIG. 5 shows operation states of the liquid crystal display panel 110 and the light modulation element 120 in the first region 201 and the second region 202, respectively.

As shown in FIG. 5, when the electronic device 100 displays an image on the liquid crystal display panel 110 (non-imaging mode), the first region 201 and the second region 202 of the light modulation element 120 are both in a scattering state. In an imaging mode in which an image is captured by the imaging device 104, the first region 201 of the light modulation device 120 is in a transparent state, and the second region 202 is maintained in a scattering state. In the imaging mode, the liquid crystal display panel 110 is driven in the same manner as when the pixels in the area corresponding to the first area 201 display white. Specifically, the alignment of the liquid crystal molecules is controlled so that the illumination light from the illumination unit 112 is transmitted in each of the red (R) pixel, the green (G) pixel, and the blue (B) pixel arranged in the region corresponding to the first region 201. As a result, the first region 201 becomes a state in which external light can enter, and the imaging element 104 performs imaging. On the other hand, even in the imaging mode, the scattering state of the light modulation element 120 is maintained in the second region 202 . Therefore, images can be displayed in the display area 114 of the liquid crystal display panel 110 corresponding to the second area 202 .

In the imaging mode, as shown in FIG. 6, the display area 114 is viewed black because the area corresponding to the first area 201 is not illuminated by the light modulation element 120, and a normal image is displayed in the area corresponding to the second area 202. External light is incident on the image sensor 104 in the first region 201, so that an image can be captured. Note that the shape of the first region 201 is arbitrary and is not limited to the shape shown in FIG.

After that, when shifting to the non-imaging mode, the first region 201 of the light modulation element 120 transitions to the scattering state. Thereby, the liquid crystal display panel 110 displays a normal image in areas corresponding to the first area 201 and the second area 202 .

FIG. 7 shows an example of an operation of capturing an image while electronic device 100 displays an image. FIG. 7 shows the operation of the liquid crystal display panel 110 and the light modulation element 120 in each of the first area 201 and the second area 202 for each frame.

As shown in FIG. 7, when the electronic device 100 performs imaging with the imaging device 104, one frame includes an image display period and an imaging period. Specifically, in the first region 201, an image display period during which the liquid crystal display panel 110 displays an image within one frame, and an imaging period during which the pixels are driven to perform white display (the display area 114 is not illuminated by the light modulation element 120 and is visually recognized as black display as shown in FIG. 6) are provided. In the first region 201 , the light modulation element 120 is controlled between a scattering state period and a transparent state period in synchronization with the operation of the liquid crystal display panel 110 . In the second area 202, the liquid crystal display panel 110 displays an image, and the light modulation element 120 is controlled to the scattering state.

When the frame frequency of the liquid crystal display panel 110 is 60 Hz, the time per frame is 16.7 msec. Here, if the shutter speed of the image sensor 104 is 1/1000 second, even if the imaging period is set to 1 msec, the imaging period can be provided within one frame without affecting image display. Note that FIG. 7 shows an example in which an imaging period is provided after an image display period, but the imaging period can be arbitrarily provided within one frame. For example, an imaging period can be provided at the beginning of one frame period, or an imaging period can be provided in the middle of one frame period.

In this way, by providing an imaging period within one frame period, it is possible to perform imaging while displaying an image over the entire display area 114 of the electronic device 100 . Since the imaging period is set as a part of time within one frame period, imaging can be performed without affecting the user's vision.

FIG. 8 shows the relationship between the polarizing plate provided in the liquid crystal display device 102, the light emitted from the illumination unit 112, and the external light. In the liquid crystal display device 102, a transmissive polarizing plate 142 is arranged on the surface of the liquid crystal display panel 110 on the cover panel 106 side, and a first reflective polarizing plate 144 is provided on the surface on the lighting unit 112 side. A second reflective polarizing plate is provided between the lighting unit 112 and the imaging element 104 .

FIG. 8 shows the X, Y and Z axes in the drawing. At this time, the direction along the Y-axis is called the first direction, the direction along the Z-axis perpendicular to the Y-axis is called the second direction, and the direction along the Y-axis and the X-axis perpendicular to the Z-axis is called the third direction. In other drawings, when the X-axis, Y-axis, and Z-axis are shown in the same way, they are treated in the same way.

The transmission polarizer 142 has a transmission polarization axis in the first direction. The first reflective polarizer 144 is arranged to have a transmission polarization axis in a second direction perpendicular to the first direction and a reflection polarization axis in the first direction. That is, the transmission polarization axes of the transmission polarizing plate 142 and the first reflective polarizing plate 144 are arranged in crossed Nicols. The second reflective polarizer 146 is arranged to have a transmission polarization axis in a second direction crossing the first direction and a reflection polarization axis in the first direction. That is, the first reflective polarizer 144 and the second reflective polarizer 146 are arranged so that the transmission polarization axes are parallel.

FIG. 8 also shows the case where the liquid crystal layer 128 of the liquid crystal display panel 110 is of the horizontal electric field type. In this case, the liquid crystal molecules are aligned in the first direction when a predetermined voltage is not applied to the pixel electrode 126, and are aligned in the second direction when a predetermined voltage is applied.

The light emitted from the light source 118 is scattered by the light modulation element 120 and part of it is irradiated to the liquid crystal display panel 110 side. Among the irradiated light, the polarized light component parallel to the transmission polarization axis of the first reflective polarizing plate 144 is transmitted, and the liquid crystal display panel 110 is irradiated with the polarized light component. On the other hand, the light reflected by the first reflective polarizer 144 does not pass through to the imaging device 104 because the polarization axis is perpendicular to the transmission polarization axis of the second reflective polarizer 146 . Therefore, the imaging element 104 is arranged in a state where it is less susceptible to the illumination light emitted by the illumination unit 112 .

Illumination light for the liquid crystal display panel 110 enters the liquid crystal layer 128 . A pixel electrode 126 is provided for each pixel in the liquid crystal display panel 110 . At this time, since the polarization axis of the illumination light is not twisted in the pixel where the voltage for aligning the liquid crystal molecules is not applied to the pixel electrode 126, the polarization direction is perpendicular to the transmission polarization axis of the transmission polarizing plate 142 and is not emitted to the viewing side. On the other hand, in a pixel in which a voltage for aligning the liquid crystal molecules is applied to the pixel electrode 126, when the irradiation light passes through the liquid crystal layer 128, the polarization axis is twisted by 90 degrees, so that the polarization axis becomes parallel to the transmission polarization axis of the transmission polarizing plate 142 and is emitted to the viewing side. Thus, the liquid crystal display device 102 displays an image on the display area 114 by controlling the voltage of each pixel. At this time, since the liquid crystal display device 102 is provided with the second reflective polarizing plate 146 , even when an image is displayed on the display area 114 , the imaging device 104 can be prevented from being affected.

FIG. 9 shows a state in which a voltage for aligning liquid crystal molecules is applied to pixels arranged in a region corresponding to the first region 201 that overlaps with the image sensor 104, and the entire light modulation device 120 is controlled to a scattering state. The polarization axis of external light transmitted through the pixels arranged in the region corresponding to the first region 201 is twisted by 90 degrees in the liquid crystal layer 128 . As a result, the polarization axis of the transmitted light that has passed through the liquid crystal display panel 110 is parallel to the transmission polarization axis of the first reflective polarizer 144 . In this state, external light is applied to the light modulation element 120 . However, since the light modulation element 120 is controlled to be in a scattering state, external light does not reach the imaging element 104 directly.

FIG. 10 shows a state in which a voltage for aligning liquid crystal molecules is applied to pixels arranged in a region corresponding to the first region 201 overlapping with the image sensor 104, and the first region 201 of the light modulation element 120 is controlled to a transparent state and a second region 202 is controlled to a scattering state. In this state, the polarization axis of the light transmitted through the transmission polarizer 142 is twisted by 90 degrees, and the light transmitted through the liquid crystal display panel 110 is polarized in the same direction as the transmission polarization axis of the first reflective polarizer 144 . Since the first region of the light modulation element 120 is controlled to be transparent, the light transmitted through the first reflective polarizing plate 144 is transmitted through the light modulation element 120 . Furthermore, since the transmission polarization axis of the second reflective polarizer 146 is parallel to the first reflective polarizer 144 , the light transmitted through the light modulation element 120 enters the imaging element 104 . As a result, external light is incident on the imaging device 104, and an image of the front of the liquid crystal display panel 110 can be captured.

Thus, according to an embodiment of the present invention, by placing the second reflective polarizer 146 between the illumination unit 112 and the imaging element 104, the imaging element 104 can be prevented from being affected by the illumination light. In addition, by arranging the transmission polarizing plate 142 and the first reflective polarizing plate 144 with the liquid crystal display panel 110 interposed therebetween so that the transmission polarization axes are crossed Nicols, and by controlling the scattering state of the light modulation element 120 in synchronization with the pixels, it is possible to image the front of the liquid crystal display panel 110 with the image pickup element 104 while displaying an image.

FIG. 11 shows an example of a functional configuration of electronic device 100 as a block diagram. The electronic device 100 includes a liquid crystal display device 102 , an image sensor 104 , a control circuit 148 , an image processing circuit 150 , a lighting control circuit 152 , an image sensor control circuit 154 , a readout circuit 156 , a memory circuit 158 and a touch sensor control circuit 160 . The liquid crystal display device 102 includes a liquid crystal display panel 110 and an illumination unit 112 . The liquid crystal display device 102 also includes a touch sensor 111 arranged over the liquid crystal display panel 110 . The function of the touch sensor 111 may be built into the liquid crystal display panel 110 .

The control circuit 148 operates based on an operating system. The control circuit 148 reads data from the memory circuit 158 and controls the image processing circuit 150 to display an image on the liquid crystal display panel 110 . For example, the control circuit 148 outputs operation screen data to the image processing circuit 150 . The image processing circuit 150 operates to display an operation screen on the liquid crystal display panel 110 based on the operation screen data. Also, the control circuit 148 is supplied with a video signal obtained via an electric communication line. The control circuit 148 outputs a video signal to the image processing circuit 150, and the image processing circuit 150 outputs the video signal to the liquid crystal display panel 110 to display an image. The control circuit 148 also reads an application program from the storage circuit 158 and outputs data for executing the application program to the image processing circuit 150 . Image processing circuit 150 outputs to liquid crystal display panel 110 an image to be displayed when the application program is executed. When the control circuit 148 outputs data for displaying an image to the image processing circuit 150, the control circuit 148 also outputs a command to the lighting control circuit 152 to drive the lighting unit 112 in synchronization therewith.

The touch sensor control circuit 160 drives the touch sensor 111 and outputs detection signals to the control circuit 148 . Based on the detection signal output from the touch sensor control circuit 160, the control circuit 148 outputs data for rewriting the content of the operation screen to the image processing circuit 150, and also controls the execution state of the application program.

For example, when execution of an application program for imaging is selected by the touch sensor control circuit 160, the control circuit 148 outputs to the image processing circuit 150 a command for causing the liquid crystal display device 102 to transition to imaging mode. The image processing circuit 150 outputs image data in which pixels in a region overlapping with the image sensor 104 are displayed in white. The control circuit 148 also outputs a command to the illumination control circuit 152 to transition to the imaging mode. The illumination control circuit 152 controls the illumination unit 112 so that the area overlapping the imaging element 104 is in a transparent state. The control circuit 148 also outputs a control signal to the image sensor control circuit 154 so as to synchronize the operations of the image processing circuit 150 and the illumination control circuit 152 . The imaging device control circuit 154 drives the imaging device 104 based on the control signal.

The operations of the liquid crystal display device 102 and the image sensor 104 in imaging mode are the same as those described with reference to FIGS. An image captured by the imaging element 104 is read by the readout circuit 156 and stored in the storage circuit 158 . Further, the image data read by the read circuit 156 may be directly input to the control circuit 148 and displayed on the liquid crystal display device 102 in real time by the image processing circuit 150 .

The control circuit 148, the image processing circuit 150, the illumination control circuit 152, the readout circuit 156, the touch sensor control circuit 160, and the imaging device control circuit 154 are realized by an arithmetic processing unit formed by a semiconductor integrated circuit. Each of these functional blocks may be integrated in one CPU, or may be realized by mounting a plurality of dedicated integrated circuits such as microprocessors and image processors on a motherboard. Also, the storage circuit 158 is realized by a semiconductor memory. The semiconductor memory is realized by a volatile dynamic memory and a non-volatile flash memory.

As described above, according to an embodiment of the present invention, by using the light modulation element 120 in the illumination unit 112, it is possible to provide an illuminated area and an unilluminated area on the liquid crystal display panel 110. FIG. The light modulation element 120 makes the area in which the liquid crystal display panel 110 is not illuminated transparent, so that the imaging element 104 arranged over this area can image the area in front of the liquid crystal display panel 110. With such a configuration, the electronic device 100 according to one embodiment of the present invention can arrange the imaging device 104 behind the liquid crystal display panel 110 . As a result, the electronic device 100 according to the embodiment of the present invention can have a narrower frame.

In one embodiment of the present invention, the electronic device 100 may be provided with an optical sensor (illuminance sensor, ambient light sensor) instead of the imaging device 104 . Further, in one embodiment of the present invention, the electronic device 100 may be provided with a plurality of regions in which the light modulation elements 120 are controlled to be in a transmissive state, and the imaging elements 104 and the optical sensors may be arranged respectively. As a result, the imaging element 104 and the optical sensor do not have to be arranged in the frame portion of the housing 108, so that the frame can be narrowed.

DESCRIPTION OF SYMBOLS 100... Electronic equipment, 102... Liquid crystal display device, 104, 105... Imaging element, 106... Cover panel, 108... Housing, 110... Liquid crystal display panel, 111... Touch sensor, 112... Illumination unit, 114... Display area, 116... Non-display area, 118... Light source, 120... Light modulation element, 122... First substrate, 124... Second substrate, 126... Pixel electrode, 128... Liquid crystal layer, 1 30 Third substrate 132 Fourth substrate 134 Light control layer 136 Liquid crystal molecule 138 First electrode 140 Second electrode 142 Transmissive polarizing plate 144 First reflective polarizing plate 146 Second reflective polarizing plate 148 Control circuit 150 Image processing circuit 152 Illumination control circuit 154 Image sensor control circuit 156 Readout circuit 158 Storage circuit 160 ... touch sensor control circuit, 201 ... first region, 202 ... second region

Claims (6)

a liquid crystal display panel having a display area in which a plurality of pixels are arranged;
an imaging device arranged on the back side of the liquid crystal display panel and capturing an image of the front through the liquid crystal display panel;
an illumination unit that includes a light modulation element disposed between the liquid crystal display panel and the imaging element and overlapping the display area, and a light source that illuminates the light modulation element;
having a first reflective polarizing plate arranged on the lighting unit side of the liquid crystal display panel and a second reflective polarizing plate arranged between the imaging element and the light modulation element;
has
The electronic device, wherein the imaging device is arranged in an area overlapping with the display area. 2. The electronic device according to claim 1, wherein the light modulation element is controlled to a scattering state in which the light emitted from the light source is scattered in the direction of the liquid crystal display panel, and a transmission state in which a region overlapping the imaging device is made transparent and other regions maintain the scattering state. 3. The electronic device according to claim 2, wherein said transmissive state is a partially transmissive state in which an area in front of said imaging element is partially transparent. 3. The electronic device according to claim 2, wherein an image is displayed on said liquid crystal display panel in said scattering state, and said liquid crystal display panel performs white display in a region overlapping with said imaging device in said transmissive state, and performs imaging with said imaging device. 2. The electronic device according to claim 1, wherein said light modulation element is a polymer dispersed liquid crystal panel. a transmissive polarizing plate disposed on a surface of the liquid crystal display panel opposite to the first reflective polarizing plate;
transmission polarization axes of the first reflective polarizing plate and the transmission polarizing plate are arranged in crossed Nicols;
2. The electronic device according to claim 1, wherein transmission polarization axes of said first reflective polarizing plate and said second reflective polarizing plate are parallel to each other.

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